Local Muscle Temperature Alters the Rate of Post-Exercise Glycogen Resynthesis

Abstract

Previous research has established that the timing and dose of ingested carbohydrates greatly influences the rate of post-exercise glycogen resynthesis. We have recently demonstrated that glycogen resynthesis is impaired in a hot ambient environment (Naperalsky et al., 2010). PURPOSE: To determine the impact of intermittent hot and cold application and the concomitant skeletal muscle temperature on rates of muscle glycogen re-synthesis after exercise. METHODS: Recreationally active male subjects (n=21) completed a 90-minute glycogen depleting ride, followed by 4 h of recovery. During recovery, two different protocols were evaluated, 1) ice was applied intermittently to one leg (IL) while the subjects other leg (CL) acted as a control (n=12) or 2) heat was applied intermittently to one leg (HL) while the subjects other leg (CL) acted as a control (n=9). Intramuscular and rectal temperature was recorded continuously. A carbohydrate (1.8 g/kg bodyweight) beverage was supplied at 0 and 2 h post exercise. Muscle biopsies (v. lateralis) were taken immediately and 4 h post exercise for the analysis of glycogen and lactate. RESULTS: The IL was colder than the CL from 15 minutes until the end recovery (p<0.05). Similarly, the HL was warmer than the CL from 15-min until the end of recovery (p<0.05). The rate of glycogen resynthesis was significantly lower in the IL compared to the CL (4.3±1.0 and 9.7±1.3 mmol/kg/hr wet wt. for the IL and CL, respectively). In contrast, the rate of glycogen resynthesis was significantly higher in the HL compared to the CL (11.7±0.8 and 8.0±1.2 mmol/kg/hr wet wt. for the HL and CL, respectively). Muscle lactate was lower in the IL after 4 h of recovery compared to the CL (1.6±0.6 vs. 2.6±0.8 mmol/L, respectively; p<0.05) but was not different between the HL and the CL (1.9±0.6 vs. 1.9±0.7 mmol/L, respectively). CONCLUSION: These data demonstrate that local muscle temperature will either reduce (intermittent ice application) or increase (intermittent heat application) rates of muscle glycogen resynthesis.